The new partner is said to be the same buyer who reportedly bought the St Regis in Aspen, Thosapong Jaruthavee, a wealthy Thai investor people refer to as “T” because his name is so hard to pronounce.

Klein refused to comment, but knowledgable sources said the deal for the 81-room hotel is valued at $75 million. Klein and Krulewitch bought the property in 2004 for $18.5 million.

“This is a win-win. Krulewitch gets to cash out, and Klein has a partner with deep pockets so he can do more deals,” said a source familiar with the negotiations.

But Stephane De Baets — Jaruthavee’s money manager, who also was involved in the Aspen deal and the launch of Chefs Club restaurants in Aspen and New York — told us: “I do not comment on the identity of my investors. Each investment you are referring to has its own limited partners structure.” And, “I manage funds in which I am the general partner.”

The investment will allow Klein and his new partner to explore other hotel purchases. Klein will retain complete control of the day-to-day running of the Sunset Tower and future properties they buy.

Another source observed of the new partner in the hotel: “Buying out Krulewitch and getting his foot in the door with Jeff is probably just the first step. I always wondered why Jeff wasn’t doing more projects. Now he will.”

Klein is also a partner in the Monkey Bar in New York with Graydon Carter and Ken Friedman. Last year, he bought West Hollywood’s San Vicente Inn.

Klein reportedly plans to spend $30 million to transform the 29-room, formerly men’s-only motel into a high-end, coed auberge.